The Siemens SENTRON 5SM3647-5KK14 is a selective residual current circuit breaker (RCCB) — 4-pole, rated 80 A at 40 °C, with a 300 mA trip threshold and Type B+ residual current sensitivity. The selective design (short-time delayed) means it coordinates with downstream RCCBs so only the faulted circuit trips, keeping the rest of the installation live.
At 50 °C it's still 76.8 A, at 60 °C it's 70.4 A, and at 70 °C it's 64 A. If your panel runs hot, use the 50 °C or 60 °C row for sizing, not the 40 °C headline. Type B+ detects smooth DC residual currents up to the rated frequency, plus AC and pulsed DC — covers VFDs, UPS systems, and EV chargers where pure AC-sensitive RCCBs would be blind. The 300 mA trip level is typical for sub-distribution or final circuits where 30 mA would nuisance-trip on leakage from filters or drives. Short-circuit withstand is 10 kA per IEC 61008-1 and EN 60898 (0.8 kA rated conditional). The let-through current is capped at 7 500 A, and the I²t value is 70 000 A²·s — useful for coordination with upstream MCBs or fuses.
The 72 mm width (4 MW) matches standard Siemens SENTRON modular devices — rows line up without adapters. IP20 with conductors connected and distribution board installed; not for wet locations. Silicon-free construction — important for automotive paint shops or semiconductor fabs where silicone outgassing can cause adhesion or contamination issues.